Automatic telephone system.



C. L. GOODRUM.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 16, 1915.

Patented Apr. 25, 1916.

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C. L. GOODRUM.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION HLED AUG-16,1915.

Patented Apr. 25, 1916.

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ln ve nfo WNW esses CHARLES I. GOODRUIVI, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application filed August 16, 1915.

To all whom it may concern Be it known that I, CHARLns L. GoooRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented. certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone systems, and more particularly to a system in which the selector switches are equipped for two movements, a directive and a hunting movement.

The object of this invention is to provide a system which utilizes a simplified and efficient selecting switch having a directive and hunting movement, and which is provided with only one motor or stepping magnet.

In the particular embodiment of the in vention herein described, the stepping magnet of the selecting switch is utilized for long and short steps. The long steps are directly controlled to select a desired group of switch terminals and the short steps to automatically hunt for an idle terminal in the selected group. The directive movement of the switch is jointly controlled by a line relay and an electromagnet, said electromagnet being jointly controlled by said line relay and a second electromagnet. The first electromagnet controls the changeover from the directive to the hunting movement of the switch, and likewise controls a stop limiting the return movement ofthe armature of the stepping magnet and hence the effective stroke of the actuating pawl of the stepping magnet.

The invention is illustrated in the accom panying drawings, in which Figure 1 illustrates the operating elements of the selecting switch, and Fig. 2' shows the preferred form of circuit arrangement with which the switch shown in Fig. 1 can be efliciently operated.

The switch, as illustrated in Fig. 1, consists of the contact terminal bank 5, in which terminals wired to other trunks or to the line wires of other telephone circuits are placed. These terminals are arranged in groups. Cooperating with these terminals is a set of brushes 6 mounted on the insulating block 7, which is rigidly attached tothe shaft 8 by the screw 9. The shaft 8 is arranged for vertical movement. 7 In this movement it carries with it the set of Specification of Letters Patent.

Patented Apr. 25, rain.

Serial No. 45,709.

brushes 6, which slide past and make contact with the terminals mounted in the terminal contact bank 5 whenever the shaft is dis placed in a vertical direction. The movement of the brush shaft 8 is directly controlled by the stepping magnet 10 which controls the actuating pawl 11. Thus, whenever the stepping magnet is energ'ized, it attracts its armature to the forward extension to which is attached the actuating pawl 11. Due to this movement of the armature of the stepping magnet, the actuating pawl 11 engages a tooth in the brush shaft 8 and moves the rod in an upward direction until the actuating pawl engages the pin 12. This movement of the brush rod will move the brush set 6 a distance equal to that occupied by one group of terminals in the terminal bank .5. When the stepping magnet 10 is de'elnergized, the armature and actuating pawl 11 will be restored to normal through the tension exerted by the spring 13. Whenever the armature of the stepping magnet moves to the end of its stroke, the insulatmg pin 14 engages the contact spring 15 and thereby breaks the contact between springs 15 and 16 and completes the contact between springs 16 and 17 The brush shaft 8 is retained in its elevated position after the actuating pawl 11 has been removed from the tooth of the brush rod 8 by the retaining pawl 20.

Associated with the stepping magnet 10 and cooperating therewith. is the electromagnet 21, which is provided with an armature having an extended arm to which is attached a catch 22. When the electromagnet 21 is energized and its armature attracted, the catch 22 will move up past the lower tooth of the rod 23. Whenever the stepping magnet 10 is energized to effect long steps of the brush rod 8, the electromagnet 21 is also operated and the energizing circuit of the stepping magnet 10 depends upon the continued operation of the electromagnet 21. When the stepping magnet 10 has made its final long step, it is locked in its actuated position with the actuating pawl 11 resting against the stop pin 12,and as the electromagnet 21 is also operated at this time, the catch 22 is moved to its elevated position and engages the lower tooth of the rod 23. Now if the electromagnet 21 is deener'gized, the consequent restoration of its armature, due to the tension of spring 25, will cause the catch 22 to move the rod 23 in a downward direction. This movement of the rod will cause the stop pin 26 to move to the left about the pivot pin 27. Since the stepping magnet is energized, the stop pin 26, in its displaced position, will be effective in preventing the armature of the stepping magnet returning to its normal position; in other words, the stop 26 will reduce the effective stroke of the armature of the stepping magnet, and hence the effective stroke of the actuating pawl 11. When the effective stroke of the armature of the stepping mag net 10 has been reduced by the stop pin 26, the pole piece of the armature will be considerably closer to the core of the electromagnet, thereby increasing the effective power of the armature and also its rapidity of action. In this displaced position of the 20 armature, the actuating pawl moves the brush rod 8 for each actuation of the armaturea distance equal to the displacement of the terminals mounted inthe contact bank 5. The insulating pin II Will function the same when the armature is in its displaced position as when the armature is in its normal position, since the movement of the contact spring is not effected until the armature reaches the end of its stroke. When the rod 23 has been drawn down by the action of the catch 22, the upper tooth'of said rod will engage pin 30 on the arm 31 and, consequently, any subsequent movement of the armature of electromagnet 21 will not disturb the position of rod 23.

The operating elements of the switch are restored to normal by the operation of the release magnet 34,. The attraction of the armature of the release magnet withdraws the retaining pawl from the tooth of the brush rod 8, and likewise moves to the left the arm 31 which is rigidly attached to the retaining pawl 20 by the pin 36. This re leases the rod 23 which will be restored to normal by the action of the spiral spring 37. The restoring of the stop 26: will restore the armature of the stepping magnet 10 to normal. Attachedto the catch 22 is a pin 40, which will engage the arm 31 in its movement to the left and thus move the catch 22 out of the path of the tooth on the rod 23.

The operating elements of the switch structure having been explained in connec tion with Fig. 1, it now becomes essential to describe the operation of said switch in connection with the circuit disclosed in Fig. 2. In the circuit shown in Fig. 2 only the operating elements of one selecting switch are shown, but .it will be obvious to anyone skilled in the art that several of these switches could; readily be inserted in the connection, their number depending upon the size of the exchange system.

When the subscriber at station 1 removes his receiver from the switchhook, a line switch or line finder mechanism will be antomatically started to hunt the exchange terminals of the calling subscribers line and connect the same to the trunks leading to a first selector switch. The line finder switch is diagrammatically shown in the diagram by means of the terminals 42 and 4:3 and the switch wipers 44 and 45. WV hen the subscribers line has been connected to the first selector switch, a circuit is completed from battery through one winding of the line relay 6L6 to the side switch wiper 47, and thence through the subscribers loop to the side switch arm 48, and through the other winding of the line relay to ground. This will energize the line relay, which will attract its armature and complete a circuit from ground through the slow acting relay 49 to battery. The calling subscriber will next operate his impulse dial to cause interruptions of the line circuit equal in number to the first digit in the desired called subscribers number. This periodic interruption of the line circuit will cause a. like number of deenergizations of the line relay 46. The first denergization of the line relay 46 will close a circuit from the ground at the armature of the relay to the armature of the relay 49 (which is a slow acting relay and will not release its armature due to the rapid fluctuation of the armature of the line relay), and thence through the coil of slow acting relay 21 to battery. Thus, the slow acting relay 21 will be operated when the L line relay 46 is restored, due to the first interruption of the line circuit. Upon the subsequent closure of the line circuit, a. circuit will be completed from the ground on the armature of the line relay 46, to the upper armature of relay 21 and thence through the stepping magnet 10 to battery. This will cause the operation of the stepping magnet which, by means of its actuating pawl, will move the brush shaft 8 a distance equal to 110 that occupied by one group of terminals in the contact bank 5. Upon each subsequent deenergization and energization of the line relay 46, the stepping magnet 10 will move the brush shaft 8 a like distance. After the last directive impulse, the stepping magnet 10 will be locked by a circuit which may be traced from battery through the stepping magnet, its contact springs 15 and 17, side switch arm 50, and the make contact spring and armature of the line relay -16, to ground.

When the slow acting relay 21 was attracted, it closed a circuit from the ground on its lower armature to side switch arm 52 and the escapement magnet 53 to battery, 135 thus operating the escapement magnet. Consequently, upon the prolonged operation of the line relay after the last impulse has been sent by the subscriber, the circuit of the slow magnet 21 is opened at the back contact of the line relay and, hence, this relay will be deenergized. Due to the restoring of its armature, the stop pin 26 will be thrown into position to limit the return movement of the armature of the stepping magnet. Likewisethe deenergization of the magnet 21 will open the operating circuit oi the escapement magnet 53 and this magnet will therefore move the side switch into its second position. When the arm 50 of the side switch moves into its second position, the locking circuit of the stepping magnet 10 will be opened and its contact spring 15 will return to normal. Then the contact spring 15 returns to normal, it closes a circuit which may be traced from battery through the stepping magnet by way of springs 15 and 16, side switch arm 54, and the make contact and armature of line relay 46 to ground. The stepping magnet thereupon closes a self-interrupted circuit at con tacts 15 and 16, by virtue of which it will automatically move the brush rod step by step until this circuit is opened.

As the stroke of the actuating pawl of the stepping magnet has been reduced by the action of the stop 26, the actuating pawl 11 will move the brush rod 8 through a series of short steps, each equal. to the displaced distance between the terminals on the contact bank 5, until an idle contact in the group selected has been found. When an idle contact is found, a circuit will be completed from battery, through the escapement magnet 53 to the side switch arm 52, the test brush 55, and thence from the test terminal found, through the test circuit of the next switch to ground. The completion of this circuit will cause the operation of the escapement magnet, which will move the side switch into its third position. When the side switch moves into its third position. it will open the seltinterrupting hunting circuit of the stepping magnet 10, and likewise its side switch arms 47 and 18 will connect the calling subscriber over the talking strands of the circuit to trunk hunting wipers 56 and 57. I

To simplify the drawing, the intermediate selector switches, as well as the connector switch between the wipers 56 and 57 and the called subscribers line, have been omitted, and in place thereof the called subscribers line has beenshown connected to the terminals which coiiperate with the switch wipers 56 and 57. To further simplify the drawing, a relay 58 is bridged to the line of the called subscriber, which is operated when the calling subscriber is connected to the trunk line terminals selected, and which controls the grounded non-busy condition of the trunk test terminal of the selected switch. This relay 58 is shown in lieu of the intermediate apparatus which would necessarily be found in a second selector switch. When the switch terminals are selected, the relay 58 is operated, and the attraction of its armature removes the ground from the test terminal of the line selected and renders it busy to other calling lines. The connection to the called subscriber may now be eX- tended in a similar manner through other selector switches and through any one of the well-known types of connector switches.

When the subscribers finish their conversation and hang up their receivers, a releasing circuit for the various switches will be completed at the connector switch in a man ner well knownin the art. This will place a ground on the test terminal of the selector switch shown in Fig. 2. .In the simplified circuit shown, the application of this ground to the test terminal is theoretically represented by the release of the armature of the bridging relay 58. Thus, when this relay is deenergized, its armature returns to normal and completes a circuit from ground over the test terminal through side switch wiper 59, vertical off-normal spring 60 and the relay 34. to battery. This will energize the release relay 34, which will attract its armature, thereby withdrawing the retaining pawl 20 and restoring the rod 2-3 and the armature of the stepping magnet 10. This will restore all of the apparatus to its normal position.

Obviously this invention. is not limited to the specific embodiment herewith shown and described, but is capable of many variations and applications without departing from its spirit and scope.

What is claimed is: I

1. In a telephone system, incoming lines and outgoing lines, a selecting switch ineluding movable contacts and stationary contacts divided into groups for extending an incoming line to an outgoing line, an impulsereceiving mechanism, a stepping magnet under the control of said receiving mechanism to move said movable contacts to a desired group of stationary contacts, an electromagnet, a stop controlled by said electroma-gnet, a locking circuit for said stepping magnet controlled by said electromagnet, and means controlled by said electromagnet to position said stop to limit the movement of the armature of said stepping magnet and to interrupt said locking circuit when the desired group of contacts has been reached.

2. In an automatic telephone system, the combination with a selecting switch of a line relay, an electromagnet controlled by said line relay. a second electromagnet jointly controlled by said line relay and said first electromagnet, a stepping magnet responsive to said line relay for the directive movement of said switch, and means controlled by said sec nd electromagnet to initiate the hunting movement of said switch and reduce the length of the actuating stroke of the armature of the stepping magnet.

3. In an automatic telephone system, the

combination with a selecting switch, of a line controlled by the electromagnet to position said stop to limit the eflective stroke of the armature of the stepping magnet and to then interrupt the locking circuit of the stepping magnet.

4. In a telephone system, the combination with a selecting switch, of a line relay. an electromagnet, a stepping magnet, said line relay and electromagnet controlling the directive movement of said stepping magnet, acontact spring on said stepping magnet effective when its armature reaches the end of its stroke to lock said magnet, a stop con trolled by said electromagnet, means con trolled by the electromagnet to position said stop to limit the return movement of the armature of the stepping magnet and to interrupt the locking circuit of the stepping magnet, said contact spring then being effective to interrupt the energizing circuit of the stepping magnet for an automatic hunting movement.

5. In an automatic telephone system, the combination with a selecting switch, of a motor magnet controlling the movement of said switch, said motor magnet being responsive to said line relay for its directive movement, a locking circuit for said motor magnet. effective after each step of said switch, and an electromagnet operable after the completion of the directive movement of said switch for interrupting said locking circuit and shortening the effective actuating stroke of the armature of said motor magneti 6. In an automatic telephone system, the combination with a selecting switch, of a line relay, an electromagnet controlled by said line relay, a second electromagnet jointly controlled by said line relay and said first electromagnet, a stepping magnet effective for giving said selecting switch a directive movement, said stepping magnet being jointly controlled by said line relay and said second electromagnet, a locking circuit for said stepping magnet effective after each step of said switch and controlled by said second electromagnet following the final directive movement of said switch, and means thereupon controlled by said electromagnet to shorten the effective actuating stroke of the armature of the stepping magnet and to initiate the hunting movement of said magnet.

7. In a telephone system, incoming lines and outgoing lines, a selecting switch for extending an incoming line to an outgoing line, an impulse-receiving mechanism, an electromagnet, a stepping magnet jointly controlled by said receiving mechanism and said electromagnet, a stop controlled by said electromagnet, a contact spring associated with said stepping magnet which is actuated when the armature of the magnet reaches the end of its stroke, said contact spring being included in a locking circuit for said stepping magnet which circuit is jointly controlled by the electromagnet and a line relay, and means controlled by said electromagnet upon the continued energization of the line relay to position said stop to limit the effective movement of the armature of the stepping magnet and to interrupt the locking circuit of the stepping magnet.

8. In a telephone system, the combination with a selecting switch, of a line relay, an electromagnet controlled by said line relay, a second electromagnet operated by the rapid energizations and deenergizations of said line relay, of a stepping magnet responsive to said rapid energization and deenergizations, a locking circuit for said stepping magnet, a stop controlled by said second electromagnet, and means controlled by said second electromagnet upon the continued energization of said line relay to position said stop so as to limit the effective stroke of the armature of the stepping magnet and to interrupt the locking circuit of said stepping magnet.

9. In a telephone system, the combination with a selecting switch. of a line relay, a stepping magnet responsive to said relay for the directive movement of said switch, and means to limit the effective stroke of the actuating armature of saidmagnet by reducing the gap between said armature and the core of said magnet whereby the speed and power of said armature are increased.

10. In a telephone system, the combination with a selecting switch, of a line relay. a stepping magnet responsive to said relay for the directive movement of said switch, an automatic hunting circuit for said magnet effective after it takes its last directive step, and means operable thereupon to limit the effective stroke of the actuating armature of said magnet by reducing the gap between said armature and the core of said magnet.

In witness whereof. I hereunto subscribe my name this 13th day of August, A. D. 1915.

CHARLES L. GOODRUM.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

Washington, D. C. 

